The present application relates generally to an improved data processing apparatus and method and more specifically to mechanisms for on-demand caching in a Wide Area Network (WAN) separated distributed file system or clustered file system cache.
Architectures exist for achieving wide area network (WAN) caching. A home site may be a general parallel file system (GPFS) or any other file system that is network file system (NFS) exported. Multiple cache sites connect to the home site over the network. Multiple cache sites can NFS mount the home NFS exports. Only one cache site is permitted to write to the files in the cache for a particular NFS export. The other sites are read-only cache sites and can see updates from the home site and pull the updates in to the cache site. However, cache sites cannot send any writes or updates to files and directories to the home site. Multiple cache sites may be the single writer for different NFS exports from the home site.